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btrfs: fix a deadlock in btrfs_scan_one_device()

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pathname resolution under a global mutex, taken on some paths in ->mount()
is a Bad Idea(tm) - think what happens if said pathname resolution triggers
automount of some btrfs instance and walks into attempt to grab the same
mutex.  Deadlock - we are waiting for daemon to finish walking the path,
daemon is waiting for us to release the mutex...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro 2011-11-17 15:05:22 -05:00
parent 6de1d09d96
commit 10f6327b5d
1 changed files with 2 additions and 3 deletions
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5
fs/btrfs/volumes.c
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@ -706,8 +706,6 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
u64 devid;
u64 transid;
mutex_lock(&uuid_mutex);
flags |= FMODE_EXCL;
bdev = blkdev_get_by_path(path, flags, holder);
@ -716,6 +714,7 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
goto error;
}
mutex_lock(&uuid_mutex);
ret = set_blocksize(bdev, 4096);
if (ret)
goto error_close;
@ -737,9 +736,9 @@ int btrfs_scan_one_device(const char *path, fmode_t flags, void *holder,
brelse(bh);
error_close:
mutex_unlock(&uuid_mutex);
blkdev_put(bdev, flags);
error:
mutex_unlock(&uuid_mutex);
return ret;
}